The objectives of the Registry of Experimental Cancers are 1) the storage and retrieval of pathologic material and data on cancers and other lesions of laboratory animals (primary rodents) and 2) the use of such information for research and educational purposes. The Registry has acquired a total of 1883 (76 since the 1979 report) single or group accessions from investigators outside the NCI. Approximately 53,200 (3,200 since the 1979 report) records have been prepared for coding and coded. Thirty-two investigators have come to the Registry for study and consultation on single or multiple visits. Two foreign investigators were at the Registry for 2 days and 3 weeks respectively.